1. Technical Field of the Invention
This invention relates to perfumed, aqueous microemulsion compositions which are low in volatile compounds. These compositions can be used e.g. in fragrances, Eaux de Toilette and cosmetic formulations.
2. Background of the Invention
The need to have cosmetically acceptable, low or zero ethanolic fragrance formulations is due to concerns about volatile organic compounds (VOCs), which are claimed to produce ground level ozone under certain extreme weather conditions. Fragrance compositions such as Eaux de Toilette containing fragrances at levels of 0.5% or above are most commonly solubilised with ethanol. However, ethanol is considered to be a VOC under many current and pending regulations. By “VOC” we mean the Volatile Organic Compounds as defined by the Environmental Protection Agency, and in particular we mean C1-C5 alkanols, such as ethanol, and the more volatile glycols such as ethylene glycol, or 1,2- and 1,3-propylene glycols.
The task of producing low or zero VOC fragrance formulations, which resemble an ethanolic fragrance composition in terms of skin feel, solution clarity, which is storage stable under various conditions such as repetitive freeze thaw cycling, and which exhibits high temperature stability, is difficult. The difficulty increases as the proportion of fragrance within the composition increases. Low VOC fragrance formulations are formulations which are substantially free of ethanol and other solvents classed as VOCs.
Blakeway (Perfumer & Flavorist, 18, January/February, p. 33, 1993) reviews the solution of perfumes using solubilisers, in particular, non-ionic surface active agents. The formulations described by Blakeway require high ratios of surfactant to perfume oil which leave a sticky feeling on the sin and can produce unwanted levels of product foaming.
Microemulsions represent one approach to producing clear, transparent products. For example, U.S. patent application 2008/023569 describes microemulsion compositions including fragrance as the oil phase, anionic and nonionic surfactants together with an ionic solubiliser. European patent application EP-A-571677 relates to clear oil-in-water microemulsions comprising a perfume oil, an aqueous phase and a surfactant, wherein the perfume/surfactant weight ratio is in the range of 0.85 to 2.5. Example 6B shows a microemulsion with a low amount of perfume (0.5 wt %), wherein the weight ratio of nonionic surfactant to anionic surfactant is 50. U.S. Pat. No. 5,585,343 describes low VOC perfume microemulsions comprising a combination of an anionic surfactant and a highly water soluble, hydrophilic coactive solvent such as a glycol or a polyol. International patent application WO 2005/123028 describes fragrance microemulsions comprising a nonionic surfactant, an anionic surfactant and vicinal diol as co-solvent. All the examples use single alkyl chain surfactants.